1. Field of the Invention
This invention relates to apparatus for inserting a catheter into a vein, and, more particularly, to apparatus for inserting a catheter into a vein by using a single hand to guide and insert the apparatus and to use the thumb of the same guiding hand to reduce pressure in a chamber in the catheter insertion apparatus below atmospheric pressure to withdraw a sample of blood from the vein to insure that the catheter is properly inserted.
2. Description of the Prior Art
Catheters are used to administer fluids to a patient by inserting a catheter into a vein of a patient as an "indwelling" element to which fluid supplies may be secured. The catheters are connected to the supply of fluids for introduction of the fluids into the individual over a relatively long period of time. The catheter is typically made of metal or of a polymerized resin, such as polytetrafluoroethylene, polypropylene, polyethylene, or similar synthetic material.
Once the catheter is inserted into a vein, it is left in the vein for fluid insertion for as long a period of time as is practical or as required. In most cases, the length of time a catheter is left in a vein depends on the condition of the vein, which in turn is a reflection upon the age of the patient, the medical problem, and other factors. Over a period of time, a vein rejects the catheter by inflammation and clotting. This is a typical body reaction to the insertion of a foreign element.
A catheter is inserted into a vein in conjunction with, or by, a catheter insertion device which is typically a relatively long metal needle used to pierce a vein. There are primarily two types of such catheter insertion devices. One type is an internal piercing device which is disposed within a catheter and the catheter accordingly comprises an external sleeve. The second type is an external sleeve in which the catheter is disposed within the needle. The first type is more common than the second type.
After the needle and catheter have been inserted into a vein (venipuncture), the proper insertion must be confirmed by withdrawing a sample of blood from the vein. In a substantial number of times, usually about fifty percent, the needle and catheter are not properly inserted into a vein. Rather, the needle and catheter are either disposed outside of a vein or else they penetrate through a vein and into tissue about the vein. With respect to a catheter insertion apparatus of the first type, if improper insertion is made, the apparatus may be withdrawn, flushed, and reused to insert the catheter. Of the second type, where the catheter is inserted within the piercing instrument or needle, the apparatus is usually not flushed and reused, but rather a new apparatus is used for a second or subsequent try at appropriate insertion. Obviously, a reusable capability is desirable.
Once a catheter is inserted into a vein, venipuncture is determined by the flow of blood into a portion of the needle. If a vein has been appropriately entered, the venous blood will readily flow into the needle in a substantial quantity. If a vein has not been appropriately punctured, as for example when the point of the needle is not disposed in the vein but rather in tissue surrounding the vein, there will not be substantial flow of blood into the needle, but rather only a scanty flow of blood. To assist in the flow of blood from the vein into the needle, suction or low pressure apparatus may either be the result of the operator operating a plunger or piston outwardly to reduce the pressure within a syringe secured to the needle, or by piercing a membrane covering a low pressure tube, using a rubber covered, partially evacuated piston or syringe ampule into which the blood flows.
Two hands of an operator are required to insert the needle and catheter and to withdraw a sample of blood to insure venipuncture. Typically, a needle and catheter are inserted into a vein by an operator holding the catheter and needle in one hand, referred to as the first hand, and using the other hand, referred to as the second hand, to hold and palpate a vein. After locating the vein into which the catheter is to be inserted, the needle and catheter are slowly inserted by the first hand while the second hand remains holding the patient's arm or leg, thereby making certain that the vein is in proper alignment for the insertion. After venipuncture has been accomplished, two hands are still required to withdraw the blood from the vein in order to ascertain venipuncture. The operator releases hold of the patient's arm or leg by the second hand and grasps the syringe secured to the needle with the second hand, and then releases the hold on the syringe by the first hand. The first hand is then transferred to the piston or ampule of the syringe, while the second hand holds the syringe. The first hand then moves the ampule or piston to appropriately withdraw blood.
During the change of holds on the syringe, with the catheter insertion apparatus in the arm, and on the subsequent movement of the piston or ampule of the syringe, the needle may puncture a wall of the vein and thus prevent appropriate catheter insertion, even though proper venipuncture was originally accomplished. In a substantial number of cases, the puncturing of the vein is accomplished properly originally, and then in the withdrawal of blood operation to confirm the venipuncture, the venipuncture is lost or destroyed by piercing a wall of the vein.
The apparatus of the present invention comprises apparatus for inserting a catheter using a single hand to both insert the catheter and to withdraw the sample of blood. It accordingly overcomes the problem of the prior art which requires the changing of hands from the initial insertion of the apparatus to perform the function of withdrawing blood to confirm venipuncture.
U.S. Pat. No. 3,323,523 illustrated one type of catheter insertion apparatus in which capillary action only is used to assure venipuncture. The catheter is inserted into a vein using a cannula for the insertion and the catheter is disposed within the cannula. The cannula inserts includes a small diameter portion for ascertaining venipuncture which is vented to atmospheric pressure and accordingly fills with blood as a result of capillary action from the blood pressure of the patient. No separate pressurized compartment or other provision is used for collecting the venous blood. This is a relatively slow and unreliable method of confirming venipuncture, and this method is not widely used.
In U.S. Pat. No. 3,335,723, a catheter is inserted within a needle, with the needle as an external sleeve, with provisions for a flexible bulb flashback device connected to the catheter and needle. The flashback device is squeezed prior to insertion into the vein of a patient and is released to allow a supply of venous blood to flow into the needle to ascertain or confirm venipuncture.
U.S. Pat. No. 3,734,095 illustrates still a third type of catheter insertion apparatus which includes a needle disposed within a catheter and the needle is connected to a tab portion which is squeezed prior to and during venipuncture and released after venipuncture has been accomplished. The tab portion then includes a low pressure area which causes blood to be withdrawn from the vein into the tab.
The three types of apparatus typically require the use of both hands during the insertion and confirmation. A fourth style, and more used than the above three, is the typical apparatus described previously where the piston of a syringe is moved rearwardly to cause a low pressure area or partial vacuum in the syringe and into which area the blood flows. Again, as with the three patents described, two hands are required to operate the apparatus after venipuncture has been accomplished.